1. Field of the Invention
The present invention relates to an object (a product including a machine, a manufacture, and a composition of matter) and a method (a process including a simple method and a production method). In particular, the present invention relates to a power storage device, a control system of a power storage device, a power storage system, an electronic circuit, a semiconductor device, a display device, a light-emitting device, and an electrical appliance, and further to a driving method thereof and a manufacturing method thereof. More specifically, the present invention relates to a power storage device, a control system of a power storage device, a power storage system, an electronic circuit, a semiconductor device, a display device, a light-emitting device, and an electrical appliance which include an oxide semiconductor, and further to a driving method thereof and a manufacturing method thereof.
2. Description of the Related Art
In recent years, various power storage devices such as secondary batteries including lithium-ion secondary batteries and the like, lithium-ion capacitors, and air cells have been actively developed (e.g., Patent Document 1). In particular, demand for lithium-ion secondary batteries with high output and high energy density has rapidly grown with the development of the semiconductor industry, for electrical appliances, for example, portable information terminals such as mobile phones, smartphones, and laptop computers, portable music players, and digital cameras; medical equipment; next-generation clean energy vehicles such as hybrid electric vehicles (HEVs), electric vehicles (EVs), and plug-in hybrid electric vehicles (PHEVs); and the like. The lithium-ion secondary batteries are essential as rechargeable energy supply sources for today's information society.
As another example of the conventional power storage device, there is a power storage system in which a plurality of battery cells is connected in series (e.g., Patent Document 2).